Exam 3: GI 1-2 Flashcards
What are the 2 parts of the GIT?
Gi Tract
Accessory organs
What are the 6 major functions of the GIT
- Transportation
- Digestion
- Absorption
- water and electrolyte balance
- Immunologic barrier
- Thermoregulation
First act of digestion, involves the actions of the teeth, the jaws, the tongue, and the cheeks
Mastication
Food intake
prehension
What are the 4 functions of the motility of the GI tract?
- propel ingesta
- retain ingesta at given site
- break up food
- circulate ingesta so all contacts sufaces
What is the first motility pattern in the GIT
Deglutition
What are the 2 phases of degllutition?
- voluntary (oral phase)
2. involuntary (swallow reflex)
difficulty swallowing
dysphagia
What are the 2 types of dysphagia?
- oropharyngeal
2. esophageal
What is oropharyngea dysphagia?
malfunction of the pharynx and upper esophageal sphincter
What is esophageal dysphagia?
due to malfunction of esophagus
a dysphagia in which food particles/fluids or stomach contents reach the upper airways
Aspiration
Regulatory center for energy homeostasis?
hypothalamus
What part of the hypothalamus is the hunger centers?
- nuclear paraventricularis
- lateral hypothalamus fields
- perifornical region
What part of the hypothalamus is the satiety center
- nuclear ventromedialis
Which hormone inhibits hunger and inc. energy consumption?
Melanocyte stimulating hormone (MSH)
What two neuropeptiedes stimulates the appetite center?
neuropeptide y (NPY) orexin
What non-hypothalamic hormone stimulates the appetite center?
Ghrelin
What 4 non-hypothalmic hormones inhibit the hunger center?
- Cholecystokinin (CCK)
- Peptide YY (PYY)
- Leptin
- Insulin
What are the 2 categories of salivary glands?
- major salivary glands
2. small salivary glands
What are the 3 types of secretions of salivary glands?
- Serous
- mucous
- seromucous
What are the 3 most important salivary glands in animals?
- parotid
- mandibular
- sublingual
What are the 4 functions of saliva?
- protection
- deglutition
- enzymatic digestion
- pH regulation
What are 3 secondary funtions of saliva?
- immunologic function
- thermoregulation
- defense (Llamas)
What does saliva consist of?
Water and electrolytes
Where is primary saliva produced?
in the acinus
Where is secondary saliva produced?
ducts
What is primary saliva composed of?
H2O, Na, Cl
What is secondary saliva composed of?
K, HCO-
What PSNS receptors are responsible for regulation of saliva secretion?
M3 receptors
What SNS receptors are responsible for regulation of saliva secretion?
a1 receptors
What are the 2 types of stimulation of saliva secretion.
- innate
2. conditioned
what is innate saliva secretion?
released through contact with bucal mucosa
What is conditioned saliva secretion?
released through sight, smell, or imagination of food
which of the following structures is elevated during deglutition to prevent food entrance into the nasal cavity?
a. Epiglottis
b. soft palate
c. hard palate
d. tongue
b. soft palate
Which of the following concerning saliva is not correct?
a. primary saliva is produced in the acinus cells
b. in the ducts more Cl is secreted into the lumen
c. in carnivorous, high saliva production leads to an inc. of electrolyte concentration
d. the PSNS stimulates saliva secretion
b.
Atropine is an anticholinergic drug used in some anesthetic protocols. Which effects would you expect on saliva production when using this drug?
a. An inc in saliva production
b. A reduced saliva production
An unchanged saliva production
b.
What are the 4 routs by which endocrine/paracrine secretions of the GI reach their targets
- Endocrine secretions
- Paracrine secretions
- Autocrine secretions
- Neurocrine secretions
Secretions are deposited close to blood vessels, and then blood carries the substances to their targets
Endocrine secretions
Substances diffuse through the interstitial space to affect other cells
Paracrine substance
Substances of a given cell regulate functions of the same cell
Autocrine substances
Refers to secretion by enteric neurons that affect muscle cells, glands, and blood cells
Neurocrine
What are the 3 determinining factor of hormones?
- must be secreted by one cell and affect another
- must be transported into the blood
- must be stimulated by food and its action must be mimicked by a synthetic analog molecule
What are the big 5 GIT hormones?
- Secreting
- Gastrin
- CCK
- GIP
- Motilin
Where is secretin produced mostly?
duodenum
What is the main synthesis site for Gastrin?
Antrum
What is the main synthesis site for CCK
all of small intestine
What is the main synthesis site of GIP and Motilin?
Duodenum and jejunum
Which hormones can be synthesized in the duodenum?
all 5
Secretin, Gastrin, CCK, GIP, Motilin
Which hormones can be synthesized in teh antrum?
gastrin
Which hormones can be produced int The jejunum?
Some secretin
CCK
GIP
Motilin
Which hormones can be produced in the ileum?
CCK
Which hormone stimiulates bicarbonate secretion and inhibits acid secretion?
Secretin
Which hormones stimulates acid secretion
Gastrin
Which hormones stimulates pancreatic enzyme secretion and gallbladder contraction
CCK
Which hormone inhibits gastric secretion and stimulates insulin secretion
GIP
Which hormone is important for induction of intestinal motility during fasting?
Motilin
What are the 3 glandular zones of the stomach?
- Cardis
- Fundus
- Pylorus
What is produced in the Cardis zone of the stomach?
Mucus
What is produced in the Fundus of the stomach?
HCL and enzymes
What is produced in the pylorus of the stomach?
mucus
The glandular mucosa of the stomach has invaginations called:
Gastric pits
What do the surface mucous cells covering the surface and lining of the stomach produce?
Thick mucus to protect from acid
what cell type is located at the neck of the gastric pits?
parietal cells
What cells are the progenitor cells for the gastric mucosa
mucous neck cells
What do the parietal cells secrete?
HCL and pepsinogen
What is secreted by parietal cells that is essential for vit. B12 absorption in the ileum?
Intrinsic Factor
All functional cell types of the gastric pit originate from this stem cell:
mucous neck cells
What are the 5 cell types that can be found in the gastric pit?
- surface mucous cells
- marietal cells
- mucous neck cells
- enterochromaffine cell
- chief cells
What do chief cells produce?
pepsinogen
What is the function of enteroendocrine cells?
secretion of endocrine substances
What are the 3 types of enteroendocrine cells and what do they produce?
- G cells- Gastrin
- D cells - Somatostatin
- I cells - CCK
What is the function of the mucous producing cells in the stomach?
secretion of mucous through exocytosis
HCl Secretion is regulated at 3 levels:
- neural
- hormonal
- paracrine
How is HCl neurally regulate?
Mediated by acetylcholine
How is HCl hormonally regualted?
Mediated by gastin
How is HCl paracrine regulated?
mediated by histamine
What are stimulatory substances for HCL secretion?
- gastrin
- histamine
- acetylcholine
What are the inhibitory substances for HCL?
somatostatin
The enzymatic secretion of gastric enzymes will be stimulated at two levels:
- neural
2. hormonal
How are gastric enzymes stimulated neurally?
- ach
2. NA
How are gastric enzymes stimulated hormonally?
- Secretin
2. CCK
If you have a Dec of pH in the stomach, you will have an inc/dec in secretion?
Increase
What stimulates mucus secretion in the stomach?
AcH and PGE
Which drug types blok the synthesis of prostaglandines
NSAIDs
What do NSAIDs stimulate the formation of in the stomach?
Gastric ulcers
What is the problem with helicobacter pylori in the stomach?
colonizes the mucose, goes under the mucus layer and synthesize urease, making a neutral microenvironment
What enzymes is produced in the stomach with the help of helicobacter pylori?
urease
What are the 3 phases of gastric secretion?
- cephalic
- gastric
3 intestinal
What happens in the cephalic phase of gastric secretion?
before food enters,
sight, smell, taste
the greater the appetite the stronger the stimulation
What happens in the gastric phase of gastric secretion?
induced by vagovagal reflexes from the stomach to the brain
dilation of the stomach, presence of AA and peptides in lumen
What happens in the intestinal phase of gastric secretion?
Induced by the presence of food in the duodenum
feedback mech.